1. Field of the Invention
The present invention relates to rotary engines, and more particularly to rotary engines of the so-called "cat and mouse" type, in which the problems attending the output/rotor-driving gearing of conventional such engines have been solved.
2. Description of the Prior Art
The Wankel engine is the principal rotary engine now in commercial use. This engine has a structure in which a substantially equilateral triangular shaped rotor rotates about an eccentric shaft, while maintaining contact with a trachoidal housing, thereby to define a rotary cycle of intake, compression, ignition, power and exhaust. Because the rotor of the Wankel engine rotates about an eccentric shaft, a counterweight is required to eliminate imbalance. Moreover, because the rotor touches the housing at the apexes of its triangular shape, it is impossible to equip the rotor with multiple gas seals.
Due to this difficulty in maintaining the air-tight sealing, and moreover due to the shape of the rotor and housing formed by a unique curved profile, the Wankel engine cannot produce the high compression ratio necessary to cause proper combustion upon receiving jets of diesel fuel. Moreover, the shape of both the rotor and the housing makes the Wankel engine difficult and expense to manufacture.
On the other hand, engines of the so-called "cat and mouse" type have been proposed, but have not found their way into commercial practice. The basic principle of the cat and mouse engine is to provide a pair of cooperating discs or rotors secured to concentric shafts, the rotors having lobes that together define the radial chambers of the engine. The rotors turn in the same direction, but the output/control gearing causes the rotors to be alternately accelerated relative to one another, such that the radial chambers undergo the cycles of intake, compression, ignition, power and exhaust.
Thus, in operation, one rotor of the engine appears to be always trying to "catch" the other, hence the name cat and mouse.
An example of this type of engine is the Murakami engine, described in U.S. Pat. Nos. 2,085,505 and 2,108,385.
In order to transmit the output of the pair of concentric shafts to a common output shaft, as well as to drive the discs in the above-described cat and mouse motion, it is necessary to provide a set of elliptical or other non-circular gears on the concentric shafts, which mesh with complementary gears provided on the common output shaft.
The principal problems preventing conventional cat and mouse engines from being commercially exploited are (1) the gears described above are subject to extreme wear, which limits the useful life of the engine, and (2) it has proven extremely difficult to seal engines of this type effectively, as there is invariably leakage of the exploding fuel-air mixture from the gas seals.
In addition to the prior art described above, there are conventional compressors and pumps that include piston and fan types and those that use root- or vane-shaped rotors; however, all of these compressors and pumps have problems with vibration or rotation speed changes, as well as maintaining air-tightness, because the rotors contact along a line.